Process for forming alloys



' Patented Jan. 1934 PATENT orrice 1,941,534 rnoonss Foa FORMING ALLOYS Jesse Oatman Better-ton, Omaha, Nebn, assignor to American Smelting and Refining Company, New York, N. Y., a corporation of New Jersey No Drawing. Application March 20, 1930 Serial No. 437,603

3 Claims. (Cl. "is-i) carbides of the above mentioned metals to a bath of molten lead under such conditions that the 115 metal is dissolved from the carbides and forms an alloy with the lead and liberates free. carbon. Special means are provided for preventing the carbides from oxidizing when they are introduced into the bath and forming an oxide coating which so would interfere with the subsequent reaction.

The invention further consists in the new and novel features of operation and the new and original arrangements and combinations of steps in the process hereinafter described and more particularly set forth in the claims.

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out in the claims appended hereto, the invention itself, as to its objects and advantages, the mode of its operation and. the

manner of its organization may be better understood by referring to the following description in which a particular commercial embodiment thereof is disclosed. It will be understood, however, that the processes and the steps thereof may be modified in various respects without departing from the broad spirit and scope of the invention.

In the following description and in the claims .40 the various steps in the process and the details comprising the invention vwill be identified by specific names for convenience but they are intended to be as generic in their application as the art will permit.

The present process is applicable to the production of alloys of lead and alkaline earth metals or metals of the magnesium group and provides for dissolving carbides of those metals in a bath of molten lead which is maintained at sufficiently high temperature to break down the carbides and form a lead alloy with the released metal.

In order to prevent the formation of an oxide coating due to the comparatively high temperature of the bath, a dissolving slag is added to the surface of the bath in sufficient quantities to completely coverthe same. This slag is capablev of dissolving any oxide whichmay be formed on the surface of the carbide particles and allowing the carbides to be introduced into the bath in a substantially clean condition. Inasmuch as an intimate surface contact is obtained between the lead and the carbide, particles, the operation may be carried on at temperatures which are sufficiently low to permit the use of standard apparatus without danger of injury thereto and at which volatilization of the metal values from the surface of the bath is substantially prevented.

As a specific example of a manner in which the present process may be carried out, a quantity of lead may be applied to a standard lead melting kettle, as for example a kettle having 16 ton-capacity, and the temperature raised suiiiciently high to melt the lead and form a molten bath. Temperatures of 535 C. to 760 C. have been found suitable for this purpose. The kettle may, if desired, be covered for the purpose for conserving heat and for preventing the final alloy from coming in contact with the air, and suitable stirring means may be incorporated in the metal for agitating the bath and forming an intimate mixture of the bath and'reagents.

Afterthe lead has been added to the kettle and melted, a dissolving slag is added to the surface thereof. This slag may consist of sodium chloride and calcium chloride. A mixture of sodium chloride with calcium chloride and magnesium chloride may also be employed. It has been found that chlorides of the alkaline earth metals or magnesium chloride together with sodium chloride in various proportions, dependent upon the particular com osition of the metal under treatment and specific operating conditions-may be employed.

These chlorides are preferably dehydrated before being applied to the lead bath. The dehydrating may be accomplished by melting the chlorides and heating the same to a temperature of 1200 F. to 1300 F. At this tempera-, ture the mass is completely liquefied and a large proportion of the water escapes as steam. A quantity of carbide such as calcium carbide representing from 5% to 15% of the weight of the fused chlorides is then added to the molten chlorides and the mixture is stirred by a suitable mixing machine. This completes the .dehydration by means of the reaction between the calcium carbide and the water or combination forming an acetylene gas which escapes as such. This dehydration is important inasmuch as complete dehydrated chlorides react more efficiently with v thereof.

the carbides which are subsequently added to the bath. a A carbide of the metal which it is desired to alloy with the lead is then added to the surface of 5 the bath and rapidly stirred therein. For forming alloys of lead 'with the alkaline earth metals or with metals of the magnesium group the carbides of these metals are applied to the bath and must pass through the slag before coming in intimate contact with the molten lead. The slag prevents exposing the metal of the bath to the air during the stirring process, thus eliminating oxidation of the alkaline earth) metals and magnesium after they are deposited in the lead. The slag also dissolves any coatings from the surface of the carbides such as the coatings which might be caused by the oxygen and nitrogen of the air and which would prevent contact between the molten lead and the carbides. The action of the 2g above mentioned dissolving slag is particularly effective and completely cleans the surface of the carbide particles whereby full and complete surface contact between the carbides and the molten lead is obtained. Under these conditions the molten lead will substantially decompose the carbides at the temperature rangeabove mentioned.

Anydesired stirring device may-be employed for causing the intimate mixture of the various nie tals. It is preferable, however, to employ a device which causes rotation of the bath and produces a vortex "in the center thereof) The carbides are then added to this vortex and are rapidly drawn under the surface of the molten lead whereby unnecessary exposure to the air is eliminated andtheir tendency to oxidize is materially decreased.

After the desired alloy has been formed, the slag may be removed from the bath whereby the o alloy may be obtained in a substantially pure condition. This separation of the slag may be accomplished in any desired manner as by skimming or by pumping the alloy from the kettle and allowing the slag to remain, on the surface It is obvious that the percentages of alkaline earth metals and of magnesium which are al-' loyed with the lead may be varied within wide limits without departing from the present process.

It is to be noted that the alloys may beformed in standard cast iron kettles by reason of the comparativelyglowtemperatures which are employed. The process is particularly usefulfor the production of alkaline earth metalfl alloys and magnesi alloys with lead or mixtures thereof in any d sired proportions.

It is to benoted that in the above mentioned process the cost is materially reduced by maingf taining the temperature sufliciently low to permit the use of standard apparatus, and furthermore,

by effecting intimate contact between clean metal surfaces whereby the efliciency of the reaction is materially increased. The invention has been 5 described as applied to particular metals by way of example only. It is obvious that it may be employed for. the production :of various other alloys bythe selection of the necessary metals and reagents. a

7 0 Although certain novel features of the invention have been .shown and described and are pointed outin the annexed claims, it will .be

, understood that various omissions, substitutions and changes in the several steps of the process 15 and in its operation may be made by those skilled in the art without departing from the spirit of the invention. C

What is claimed is: 1. The process of forming alloys of lead with metals of the alkaline earth group and magnesium which comprisesndding said metals in the form of carbide particles toa bath of molten lead, covering said molten lead bath with a protecting slag, and dissolving undesired coatings and removing impurities from the surface of said particles by means of said slag, whereby an intimate contact between carbide particles and the lead is obtained.

2. The process of forming alloys of lead with the alkaline earth metals and with magnesium which comprises applying a dissolving slag to the surface of the bath of molten lead and adding the alloyforming metal in a carbide form to said bath and rapidly stirring the same therein, whereby the dissolving slag dissolves the coating from the surface of the carbides and causes the same to enter into the bath in a clean condition. i

3. The process of forming alloys of lead with the alkaline earth metals and with magnesium me which comprises forming a bath of molten lead at a temperature range of substantially 535 C. to 760 0., adding a dissolving slag to the surface thereof of the class comprising chlorides of 'alka- I line earth metals and magnesium together with sodium chloride and applying the alloy forming metal in the carbide form to said bath, causing said metal to pass through said slag and stirring the same into the bath whereby an intimate surface contact is obtained. a I

e. The process of forming alloys of lead with an alkaline earth metal, which comprises forming a bath of lead at a temperature of approximately 535C. to 760 C., adding a slag to the surface thereof comprising a mixture of sodium chloride and calcium chloride, applying the carbide .of the alkaline earth metal to the bath, causing said carbide to pass throughsaid slag and to be thoroughly incorporated in said bath, said slag serving to remov impurities from the surface of said carbide and to permit an intimate contact between the carbide and the lead with the formation of the lead alloy and the liberation of the carbon, p

- 5. The process of forming an alloy of lead with a metal of the alkaline earth group or the magnesium group, which comprises forming a bath of lead; adding thereto a slag comprising a mixture of sodium chloride with chlorides of the alkaline earth metals or magnesium, causing said slag to cover the surface of the bath and adding thereto carbides of/the alkaline earth metals or metals of the magnesium group, passing said carbides through said slag and forming an intimate mixture thereof with the lead bath, said slag 35 serving ,to dissolve impurities from the surface of the said carbides and permitdntimate surface contact with the lead and also to prevent exposure of the metal of the bath to the air and eliminate oxidation of the alkaline earth metals and metals of the magnesium group after they are deposited in the bath.

6. The process of forming alloys'of lead with the alkaline earth metals and with magnesium, which comprises applying to a bath of molten lead a dissolving slag which covers the surface thereof and applying thereto carbides of the alloy forming metal while .maintaining the bath at a temperature to cause decomposition of the carbides with the formation of the lead metal in the carbide form to said bath, causing said 1,94nss4 I comprises melting 1, a dissolving slag oi the class metal to pass through said slag and stirring the same into the bath whereby an intimate surface contact is obtained.

8. The process of forming alloys of lead which comprising chlorides of alkaline earth metals and magnesium and sodium chloride, raising the temperature of said slag to a point at which a substantial dehydration takes place, adding a.

carbide to said slag in quantities to react with the remaining water of combination to form acetylene gas and to substantially completely dehydrate said slag, adding said slag to a bath oi. moltenlead andapplying carbides oi the alloy forming metal to said bath, said slag serving to remove impurities from the surface of said carhides and permit an intimate reaction thereof with the lead. I

' JESSE OATMAN BE'I'IERTON. 

